Mr. P is a 53-year-old man who, when younger, was actively involved in a nu
mber of sports including football, skiing and tennis. At the age of 22 year
s, he had a meniscetomy for a torn medial meniscus of the left knee. This k
nee became painful 5 years ago, especially at the end of the day. Over the
past year, the episodes of pain have increased to the point where he has cu
rtailed all recreational activity and is finding it increasingly difficult
to walk long distances. Due to his pain and the resultant inactivity, he ha
s gained 20 kg. Weight-bearing radiographs of his knee show moderate loss o
f joint space involving the medial joint compartment.